Superelastic guiding member
First Claim
1. An intravascular guidewire comprising a) an elongated member having a proximal portion and a distal portion and being formed at least in part of a superelastic alloy consisting essentially of about 30 to about 52% titanium, about 38 to about 52% nickel and up to 20% additional alloying elements selected from the group consisting of iron, cobalt, platinum, palladium, copper and vanadium, said alloy part having an austenite phase which has a final transformation temperature below about 45°
- C., which transforms to a martensite phase upon the application of stress and which has been thermomechanically formed in a procedure which includes a final cold working followed by a heat treatment at a temperature between about 450°
to about 600°
C. while applying tension to the cold worked elongated member; and
b) torquing means on the proximal end of the elongated member.
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Accused Products
Abstract
An improved guiding member for use within a body lumen having a unique combination of superelastic characteristics. The superelastic alloy material has a composition consisting of about 30% to about 52% (atomic) titanium, and about 38% to 52% nickel and may have one or more elements selected from the group consisting of iron, cobalt, platinum, palladium, vanadium, copper, zirconium, hafnium and niobium. The alloy material is subjected to thermomechanical processing which includes a final cold working of about 10 to about 75% and then a heat treatment at a temperature between about 450° and about 600° C. and preferably about 475° to about 550° C. Before the heat treatment the cold worked alloy material is preferably subjected to mechanical straightening. The alloy material is preferably subjected to stresses equal to about 5 to about 50% of the room temperature ultimate yield stress of the material during the thermal treatment. The guiding member using such improved material exhibits a stress-induced austenite-to-martensite phase transformation at an exceptionally high constant yield strength of over 90 ksi for solid members and over 70 ksi for tubular members with a broad recoverable strain of at least about 4% during the phase transformation. An essentially whip free product is obtained.
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Citations
32 Claims
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1. An intravascular guidewire comprising
a) an elongated member having a proximal portion and a distal portion and being formed at least in part of a superelastic alloy consisting essentially of about 30 to about 52% titanium, about 38 to about 52% nickel and up to 20% additional alloying elements selected from the group consisting of iron, cobalt, platinum, palladium, copper and vanadium, said alloy part having an austenite phase which has a final transformation temperature below about 45° - C., which transforms to a martensite phase upon the application of stress and which has been thermomechanically formed in a procedure which includes a final cold working followed by a heat treatment at a temperature between about 450°
to about 600°
C. while applying tension to the cold worked elongated member; and
b) torquing means on the proximal end of the elongated member. - View Dependent Claims (2, 3, 4, 5, 6, 14, 15)
- C., which transforms to a martensite phase upon the application of stress and which has been thermomechanically formed in a procedure which includes a final cold working followed by a heat treatment at a temperature between about 450°
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7. A superelastic alloy body having an austenite phase which is stable at a desired operating temperature and which will transform to martensite phase upon the application thereto of stress, exhibiting a recoverable strain of at least about 4% upon the stress induced transformation of the austenite phase to martensite phase and having been formed by thermomechanical processing which includes a final cold working about 10 to about 75% and a memory imparting heat treatment at a temperature between about 475°
- and about 600°
C. - View Dependent Claims (8, 9, 10, 11, 12, 13)
- and about 600°
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16. A fixed-wire balloon angioplasty catheter comprising:
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a) an elongated catheter body with an inner lumen extending therein;
b) an inflatable balloon on the distal extremity of the catheter body and having an interior in fluid communication with the inner lumen of the catheter body; and
c) a guiding member which is disposed at least in part within the interior of the inflatable balloon and which is formed at least in part of a superelastic alloy body having an austenite phase which is stable at a desired operating temperature and which will transform to martensite phase upon the application thereto of stress, exhibiting a recoverable strain of at least about 4% upon the stress induced transformation of the austenite phase to martensite phase and having been formed by a thermomechanical processing which includes a final cold working of about 10 to about 75% and then a memory imparting heat treatment at a temperature between about 450° and
about 600°
C. while tension is applied thereto.
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17. The fixed wire balloon angioplasty catheter of claim 17 wherein the thermomechanical processing includes a mechanical straightening between the cold working and heat treating.
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18. A method of forming a superelastic elongated member being in an austenite phase which is stable at temperatures less than about 45°
- C.;
providing an elongated member formed of an alloy consisting essentially of about 30 to about 52% titanium, about 38 to about 52% nickel and up to a total of about 20% of one or more additional alloying elements selected from the group consisting of iron, cobalt, chromium, platinum, palladium, copper, vanadium, zirconium, hafnium and niobium;
subjecting the elongated member to thermomechanical processing which includes a final cold working of about 10 to about 75% and a heat treatment at a temperature between about 450° and
about 600°
C. while subjecting the elongated member to a tension of up to about 50% of the room temperature tensile strength. - View Dependent Claims (19, 20, 21)
- C.;
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22. An elongated tubular body suitable for use within a human body which has a cylindrical wall defining an inner lumen therein, which is formed of a superelastic alloy consisting essentially of about 30 to about 52% titanium, about 38 to 52% nickel, and to about 20% of one or more elements selected from the group consisting of iron, cobalt, chromium, platinum, palladium, copper, vanadium, zirconium, hafnium and niobium in a stable austenite phase which will transform to martensite phase upon the application of stress, which will exhibit a recoverable strain of at least about 4% from the application of stress which transforms the austenite phase to the martensite phase and which has been fabricated by a thermomechanical processing which includes a final cold working of about 10 to about 75% and then a memory imparting heat treatment at a temperature of about 450°
- to about 600°
C. - View Dependent Claims (23, 24, 25, 26, 27)
- to about 600°
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28. A method of forming a superelastic elongated member having a straight memory comprising subjecting an elongated member having a composition consisting of a predominant amount of NiTi intermetallic constituent to thermomechanical processing which includes a final cold working of about 10 to about 75% and a heat treatment at a temperature between about 450°
- and about 600°
C. while subjecting the cold worked elongated member to sufficient tension to ensure a straight memory. - View Dependent Claims (29, 30, 31, 32)
- and about 600°
Specification